The present invention relates to windshield mounted antenna assemblies, and more particularly to an antenna having a relatively long effective electrical length.
Window mounted antennas have become popular in connection with local communications, particularly cellular telephone communications. One arrangement is described and claimed in my prior U.S. Pat. No. 4,238,799 for "Windshield Mounted Half-Wave Communications Antenna Assembly". While that assembly has proven to be quite effective, it has been found that, unexpectedly, a simpler and less costly circuit is capable of achieving the same superior response of the previous arrangement, while at the same time effecting considerable savings in complexity and size.
Previous attempts to design a communications antenna with reduced complexity are represented, for example, by U.S. Pat. No. 4,658,259. That arrangement uses a quarter-wavelength antenna, which demands an extensive ground plane to achieve good gain at the horizon and an omnidirectional radiation pattern. However, apparently because of its limited ground plane, this antenna had an average gain some 6 dB below the cellular version of U.S. Pat. No. 4,238,799 and an azimuthal plane pattern characterized by deep nulls.
It is accordingly desirable to provide a window mounted antenna assembly design of reduced complexity, which does not suffer the disadvantages associated with a quarter-wavelength antenna with a small assymetrical and tilted ground plane.